PEP 6305 Measurement in Health & Physical EducationTopic 13: Measuring Physical ActivityClick to go to back to the previous section (Section 13.2) Show
This section will take a look at several physiological measures of physical activity.
Heart rate monitors
One of the first objective measures of physical activity consisted of heart rate monitoring.
An advantage to heart rate monitors is the ability to have the subjects wear them just about anywhere and then download the data at a later time. The subjects are not restricted in their environment thus enabling their use for collecting physical activity data in the field or real-life settings. Disadvantages to heart rate monitors include the initial cost of purchasing the monitors and external factors that affect heart rate, such as stress and environmental conditions (heat and humidity). Motion sensors Motion sensors can be divided into two main types, pedometers and accelerometers.
The relative unobtrusiveness of motion sensors allow subjects to wear them in the field and throughout their daily lives. The initial cost of purchasing the motion sensors is a disadvantage just like heart rate monitors, but the range of cost is greater depending on the complexity of the sensor. Because data are collected using an objective method, they are usually more reliable than subjective methods such as questionnaires and diaries. Despite the sophistication of advanced motion sensors for measuring the duration and intensity of physical activity, not all activities can be measured.
Calorimetry
Direct calorimetry involves the measurement of heat produced by the body during physical activity.
Calorimeters are extremely expensive to construct and are slow to generate results. he only real advantage is that they are a direct measure of heat produced. The measurements are extremely accurate for total energy expenditure; however, direct calorimetry cannot follow rapid changes in energy usage. This method is seldom used today as it is easier and less expensive to assess energy expenditure via indirect calorimetry. Indirect calorimetry involves the measurement of respiratory gas exchange (oxygen consumption and carbon dioxide production) during a variety of controlled physical activities (cycle and treadmill exercise is common).
The main advantage of indirect calorimetry is its extreme accuracy. Therefore, indirect calorimetry is useful for compiling an activity compendium and associated energy costs. There are numerous disadvantages to indirect calorimetry: · High cost · Technical expertise necessary · Laboratory based measurement · Unsuitable for long-term measurement Doubly labeled water The doubly labeled water method can be used to measure total energy expenditure in unrestrained subjects for 1-4 weeks.
Doubly labeled water is currently the most accurate way to measure total energy expenditure and is considered the gold standard. Often it is the criterion measure that new measurement techniques are judged against. Because of the expense of the doubly labeled water method, only small populations are usually feasible without a large research grant or other funding source.
Summary
You have reached the end of Topic 13. You must complete the review quiz before you can advance to the next topic. What is the common method used to measure energy expenditure by the body?Methods of indirect calorimetry are the most commonly used to quantify human EE in both laboratory and field settings, typically by measuring O2 consumption.
What is the best method of measuring energy expenditure?The direct calorimetry technique measures the rate of heat loss by the subject using a calorimeter. It is the most accurate method for quantifying metabolic rate [39], but its use is limited by the high cost.
What is the method for determining energy expenditure that involves measuring the amount of oxygen a person uses?In indirect calorimetry, energy expenditure is determined by measuring the amount of oxygen consumed and carbon dioxide produced.
Why is VO2 used to measure energy expenditure?Consequently, the higher the VO2 consumed during the activity, the greater the energy produced. VO2 is therefore the main parameter to define the aerobic capacity of an individual, i.e. the ability to produce energy through mechanisms that require the use of oxygen.
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